High summer on Borkum, and vacationers are enjoying the beach. Hobby detective Caro Falk is also looking forward to a sunny day by the sea when a piercing scream startles the holidaymakers from their beach chairs. A small boy is standing knee-deep in the water, screaming as if he were being murdered – a severed finger is floating in his bucket. When the corresponding corpse appears shortly after, Caro's curiosity is piqued. The dead mudflat guide was a dedicated environmentalist who had some enemies on the island – and even more secrets to hide.